LCD's that have a text mode, that is the ability to send ascii text data to, have a built in character ROM, or memory storing the LCD font as it were. If your LCD doesn't have the umlauts in the character ROM, then you won't be able to display them other than through graphical representation of them.

Or.. you could get technical, and re-write the drivers so that they can write to the custom character space. But thats beyond both of us for now.

So.. Basically, find out what is in your character ROM, see if it has these characters first. To do that, you need the full datasheet for the controller on your LCD. Or, find out what controller you have and repost in here, and maybe I can find the time to go through it for you, but it might actually be quicker for you to do it yourself. And, you'll learn much more doing it that way.

The problem here is that usually even if the character generator rom would include these characters they are not in the same place in the table as in ascii. And as LCDInfo (or better would be to say the drivers as the character mapping is display dependent) doesn't yet do this kind translation / mapping they are not shown correctly. I need to work on this.